Lenticular nuclei to thalamic ratio on PET is useful for diagnosis of GLUT1 deficiency syndrome.

PURPOSE: To establish an objective method of [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) that can assist in the diagnosis of glucose transporter 1 deficiency syndrome (GLUT1-DS). METHODS: FDG-PET was performed in 8 patients with a mean age of 12.5 years (range, 2-22 years) with GLUT1-DS. Their PET findings were compared with those of 45 controls with a mean age of 11.2 years (range, 2-21 years) by statistical parametric mapping (SPM12, Welcome Neurological Institute). The controls had epilepsy of unknown etiology and normal MRI findings. The age-adjusted ratios of mean radioactivities in regions of interest (ROIs) of bilateral lenticular nuclei, thalami, and the whole cerebral cortex were also measured. The sensitivities and specificities of the ratios for the differential diagnosis of GLUT1-DS were also determined. RESULTS: SPM showed significantly decreased uptake in bilateral thalami and increased uptake in bilateral lenticular nuclei in patients with GLUT1-DS. There were no areas in the cerebral cortex with significant differences between patients and controls. On ROI analysis, by setting the cut-off value of the age-adjusted lenticular nuclei/thalami radioactivity ratio to 1.54, patients with GLUT1-DS were differentiated from controls with sensitivity of 1.00 and specificity of 0.98. CONCLUSION: The age-adjusted lenticular nuclei/thalami radioactivity ratio on PET can distinguish patients with GLUT1-DS from patients with epilepsy of unknown etiology with high sensitivity and specificity. It is important to pay attention to the metabolism of the lenticular nuclei and thalami on PET for the diagnosis of GLUT1-DS.

Variety of symptoms of GLUT1 deficiency syndrome in three-generation family.

OBJECTIVE: Glucose transporter type 1 deficiency (G1D) syndrome is generally a genetic disorder because of a mutation of the SLC2A1 gene. The clinical picture of G1D is heterogeneous. The aim of this paper was to present the case of G1D, recognized in a three-generation family, caused by missense mutation p.Arg92Trp in SLC2A1 gene, and showing high clinical heterogeneity and evolution of symptoms over time. METHODS: Three-generation family members, showing symptoms suggesting G1D, have been characterized in terms of the clinical picture, electroencephalogram (EEG) recordings, brain neuroimaging, and the psychological assessment data. All subjects were offered genetic testing of the SLC2A1 gene. RESULTS: We sequenced the SLC2A1 gene in the proband of the family and identified the c.274C > T variant (p.Arg92Trp). The presence of the same mutation was confirmed in all affected family members; however, significant variations in the clinical picture among them were observed. In addition to the typical symptoms for G1D (e.g., epilepsy, intellectual disability), patients presented movement disorders, stiffness, and dysarthria, as well as psychiatric symptoms. After using the ketogenic diet, epileptic seizures disappeared, but the rest of the symptoms were resistant to treatment. CONCLUSIONS: Despite the same underlying mutation, clinical symptoms may vary among members of one family. Different clinical symptoms are observed depending on the patient's age. Not all symptoms occur in all patients within one family despite the same genetic background. However, the importance of early therapy for the clinical course of the disease requires further study.

Diagnostic Challenges Associated with GLUT1 Deficiency: Phenotypic Variabilities and Evolving Clinical Features.

GLUT1 deficiency is a rare neurometabolic disorder that can be effectively treated with ketogenic diet. However, this condition is underdiagnosed due to its nonspecific, overlapping, and evolving symptoms with age. We retrospectively reviewed the clinical course of nine patients diagnosed with GLUT1 deficiency, based on SLC2A1 mutations and/or glucose concentration in cerebrospinal fluid. The patients included eight boys and one girl who initially presented with seizures (44%, 4/9) or delayed development (44%, 4/9) before 2 years of age, except for one patient who presented with apnea as a neonate. Over the clinical course, all of the children developed seizures of the mixed type, including absence seizures and generalized tonic-clonic seizures. About half (56%, 5/9) showed movement disorders such as ataxia, dystonia, or dyskinesia. We observed an evolution of phenotype over time, although this was not uniform across all patients. Only one child had microcephaly. In five patients, ketogenic diet was effective in reducing seizures and movement symptoms, and the patients exhibited subjective improvement in cognitive function. Diagnosing GLUT1 deficiency can be challenging due to the phenotypic variability and evolution. A high index of clinical suspicion in pediatric and even older patients with epilepsy or movement disorders is key to the early diagnosis and treatment, which can improve the patient's quality of life.

Relationship between Size of the Foveal Avascular Zone and Carbohydrate Metabolic Disorders during Pregnancy.

AIM: To determine whether the area of the foveal avascular zone (FAZ), as a morphological indicator of the microcirculation of the perifoveal capillary network, changes in the carbohydrate metabolism disorders during pregnancy (the gestational age of patients with gestational diabetes mellitus (GDM) and preexisting diabetes (PexD)). METHODS: Ten normal individuals and 41 eyes of 41 patients, 28 with GDM and 13 with PexD, were studied. A 3 × 3 mm area of the FAZ of the superficial capillary plexus layer (SCP) and the deep capillary plexus layer (DCP) was determined by optical coherence tomography angiography (OCTA; RS-3000 Advance, NIDEK). The significance of the correlation between the size of the FAZ and the weeks of pregnancy was determined. RESULTS: The area of the FAZ of the SCP was 0.38 ± 0.11 mm2 (normal eyes), 0.41 ± 0.16 mm2 (GDM), and 0.43 ± 0.10 mm2 (PexD). The area of the FAZ of the DCP was 0.78 ± 0.23 mm2 (normal eyes), 0.69 ± 0.16 mm2 (GDM), and 0.79 ± 0.25 mm2 (PexD). No significant difference in the FAZ sizes was observed between the groups. The average number of weeks of pregnancy was 24.1 ± 8.2 weeks in the eyes with GDM and 23.3 ± 11.4 weeks in the eyes with PexD (P > 0.05). Significant correlations were found between the size of the FAZ of the SCP and the number of weeks (r = 0.37, P=0.04 for GDM, and r = 0.49, P=0.04 for PexD, Spearman's rank-order correlation coefficient). CONCLUSIONS: For GDM and PexD under established glycemic control, the area of the FAZ is not affected, but vascular changes occurred at the early phase of pregnancy.

Further Delineation of Ribose-5-phosphate Isomerase Deficiency: Report of a Third Case.

Ribose-5-phosphate isomerase deficiency, a disorder of the pentose phosphate shunt, was described in 1999. There are 2 previously reported cases of ribose-5-phosphate isomerase deficiency. Here, we describe the clinical course, diagnostic odyssey, and molecular findings in the third case of ribose-5-phosphate isomerase deficiency to further delineate the syndrome. Whole-exome sequencing demonstrated 2 mutations in the ribose-5-phosphate isomerase gene, RPIA, in a child with neonatal onset leukoencephalopathy and psychomotor delays. Urine polyols were elevated confirming deficiency of ribose-5-phosphate isomerase (RPI, EC. 5.3.1.6) and pathogenicity of the variants. Measurement of urine polyols should be considered in cases of early-onset white-matter disease.

Further evidence that d-glycerate kinase (GK) deficiency is a benign disorder.

d-Glyceric aciduria is caused by deficiency in d-glycerate kinase (GK) due to recessive mutations in the GLYCTK gene. GK catalyzes the conversion of d-glycerate to 2-phosphoglycerate which is an intermediary reaction in the catabolism of serine and fructose. Deficiency of GK leads to accumulation of d-glycerate, which may be detected in urine organic acid analysis. Debate exists as to whether this is a benign or disease-causing disorder as the reported phenotypes vary significantly. We report two siblings from a consanguineous Pakistani family. The index case is a 5year old boy with severe autism and global developmental delay. His urine organic acid analysis showed markedly increased excretion of glycerate, determined as d-form by enantioselective gas chromatography. There was no oxalic aciduria. His younger sister (3years old) is asymptomatic and developmentally normal (already bilingual). Her urine showed similar amounts of d-glycerate. Both children are homozygous for the novel mutation c.767C>G in exon 5 of the GLYCTK gene, predicted to affect the enzyme by replacing the evolutionarily conserved Proline with Arginine (P256R). Both parents are heterozygous carriers. These cases support the view that d-glycerate kinase deficiency is a benign disorder. Long term follow-up studies with a greater number of individuals may be required for further confirmation.

Infantile Serine Biosynthesis Defect Due to Phosphoglycerate Dehydrogenase Deficiency: Variability in Phenotype and Treatment Response, Novel Mutations, and Diagnostic Challenges.

Serine biosynthesis defects can present in a broad phenotypic spectrum ranging from Neu-Laxova syndrome, a lethal disease with multiple congenital anomalies at the severe end, to an infantile disease with severe psychomotor retardation and seizures as an intermediate phenotype, to a childhood disease with intellectual disability at the mild end. In this report we present 6 individuals from 3 families with infantile phosphoglycerate dehydrogenase (PGDH) deficiency who presented with psychomotor delay, growth failure, microcephaly, and spasticity. The phenotype was variable with absence of seizures in 2 sisters in family 1 and 1 infant in family 2 and seizures with pronounced happy affect in 3 sisters in family 3. The initiation of serine treatment had pronounced effect on seizures and spasticity in the sisters in family 3, but minimal developmental effects on the children in families 1 and 2. With such phenotypic variability, the diagnosis of PGDH deficiency can be challenging.

Brain correlates of spike and wave discharges in GLUT1 deficiency syndrome.

PURPOSE: To provide imaging biomarkers of generalized spike-and-wave discharges (GSWD) in patients with GLUT1 deficiency syndrome (GLUT1DS). METHODS: Eighteen GLUT1DS patients with pathogenetic mutation in SLC2A1 gene were studied by means of Video-EEG simultaneously recorded with functional MRI (VideoEEG-fMRI). A control group of sex and age-matched patients affected by Genetic Generalized Epilepsy (GGE) with GSWD were investigated with the same protocol. Within and between groups comparison was performed as appropriated. For GLUT1DS, correlations analyses between the contrast of interest and the main clinical measurements were provided. RESULTS: EEG during fMRI revealed interictal GSWD in 10 GLUT1DS patients. Group-level analysis showed BOLD signal increases at the premotor cortex and putamen. With respect to GGE, GLUT1DS patients demonstrated increased neuronal activity in the putamen, precuneus, cingulate cortex, SMA and paracentral lobule. Whole-brain correlation analyses disclosed a linear relationship between the GSWD-related BOLD changes and the levels of glycorrhachia at diagnosis over the sensory-motor cortex and superior parietal lobuli. CONCLUSION: The BOLD dynamics related to GSWD in GLUT1DS are substantially different from typical GGE showing the former an increased activity in the premotor-striatal network and a decrease in the thalamus. The revealed hemodynamic maps might represent imaging biomarkers of GLUT1DS, being potentially useful for a precocious diagnosis of this genetic disorder.

Use of the Biphasic (13)C-Sucrose/Glucose Breath Test to Assess Sucrose Maldigestion in Adults with Functional Bowel Disorders.

Sucrase insufficiency has been observed in children with of functional bowel disorders (FBD) and symptoms of dietary carbohydrate intolerance may be indistinguishable from those of FBD. A two-phase (13)C-sucrose/(13)C-glucose breath test ((13)C-S/GBT) was used to assess sucrase activity because disaccharidase assays are seldom performed in adults. When (13)C-sucrose is hydrolyzed to liberate monosaccharides, oxidation to (13)CO2 is a proportional indicator of sucrase activity. Subsequently, (13)C-glucose oxidation rate was determined after a secondary substrate ingestion (superdose) to adjust for individual habitus effects (Phase II). (13)CO2 enrichment recovery ratio from (13)C-sucrose and secondary (13)C-glucose loads reflect the individualized sucrase activity [Coefficient of Glucose Oxidation for Sucrose (CGO-S)]. To determine if sucrase insufficiency could be a factor in FBD, (13)C-S/GBT was validated using subjects with known sucrase gene mutation status by comparing (13)CO2-breath enrichment with plasma (13)C-glucose enrichment. (13)C-S/GBT was used to assess sucrose digestion in FBD patients and asymptomatic controls. (13)CO2-breath enrichment correlated with the appearance of (13)C-sucrose-derived glucose in plasma (r (2) = 0.80). Mean, control group CGO-S-enrichment outcomes were 1.01 at 60', 0.92 at 75', and 0.96 at mean 60'-75' with normal CGO-S defined as >0.85 (95% C.I.). In contrast, FBD patients demonstrated lower CGO-S values of 0.77 at 60', 0.77 at 75', and 0.76 at mean 60'-75' (Chi Square: 6.55; p < 0.01), which points to sucrose maldigestion as a cause of FBD.

Topography of brain glucose hypometabolism and epileptic network in glucose transporter 1 deficiency.

RATIONALE: (18)F fluorodeoxyglucose positron emission tomography ((18)F FDG-PET) facilitates examination of glucose metabolism. Previously, we described regional cerebral glucose hypometabolism using (18)F FDG-PET in patients with Glucose transporter 1 Deficiency Syndrome (Glut1 DS). We now expand this observation in Glut1 DS using quantitative image analysis to identify the epileptic network based on the regional distribution of glucose hypometabolism. METHODS: (18)F FDG-PET scans of 16 Glut1 DS patients and 7 healthy participants were examined using Statistical parametric Mapping (SPM). Summed images were preprocessed for statistical analysis using MATLAB 7.1 and SPM 2 software. Region of interest (ROI) analysis was performed to validate SPM results. RESULTS: Visual analysis of the (18)F FDG-PET images demonstrated prominent regional glucose hypometabolism in the thalamus, neocortical regions and cerebellum bilaterally. Group comparison using SPM analysis confirmed that the regional distribution of glucose hypo-metabolism was present in thalamus, cerebellum, temporal cortex and central lobule. Two mildly affected patients without epilepsy had hypometabolism in cerebellum, inferior frontal cortex, and temporal lobe, but not thalamus. Glucose hypometabolism did not correlate with age at the time of PET imaging, head circumference, CSF glucose concentration at the time of diagnosis, RBC glucose uptake, or CNS score. CONCLUSION: Quantitative analysis of (18)F FDG-PET imaging in Glut1 DS patients confirmed that hypometabolism was present symmetrically in thalamus, cerebellum, frontal and temporal cortex. The hypometabolism in thalamus correlated with the clinical history of epilepsy.

Body composition in young patients with galactose metabolic disorders: a preliminary report.

AIM: Body composition evaluation in patients with galactosemia and its variants. METHODS: The body composition of young subjects with galactose metabolic disorders was analyzed with dual X-ray absorptiometry. The subjects were divided into the classic galactosemia (CG; n=14) group and the group with other galactose metabolic disorders (OGMD, e.g., epimerase deficiency; n=8). RESULTS: In both groups, bone strength and bone mineral density Z-scores were normal. However, CG patients appeared sarcopenic (median muscle mass Z-score=-1.93), whereas OGMD subjects had low-normal muscle mass. In addition, approximately half of all patients were overweight. In CG patients, bone mass was strongly correlated to muscle mass (r=0.81), whereas in OGMD patients it was positively correlated to body mass index (r=0.78). CONCLUSIONS: An imbalance between muscle and fat mass, especially in patients with classic galactosemia, was observed. Given the observed strong correlation between bone and muscle mass, more effective lifestyle counseling is needed.

Three Japanese patients with glucose transporter type 1 deficiency syndrome.

We report three Japanese patients with glucose transporter type 1 deficiency syndrome (Glut1DS). Two patients had a normal erythrocyte 3-O-methylglucose (3OMG) uptake, one with a previously reported T295M substitution and the other with a novel 12-bp insertion at nt 1034-1035, ins CAGCAGCTGTCT. The third patient, with deficient 3OMG uptake, had a previously reported hot-spot mutation, R333W. All three patients responded to a ketogenic diet. All patients showed a significant improvement in ataxia, with blood beta-hydroxybutyrate (BOHB) levels ranging from 0.1 to 3mM. BOHB levels of at least 3mM were necessary to control seizures, and higher ketone levels are recommended to meet brain energy needs during development. FDG-PET scan, performed before and after a ketogenic diet in the R333W patient, did not change despite a clinical improvement. This clinical condition is treatable and early diagnosis is important.

Congenital disorders of glycosylation type I: a rare but new cause of hyperechoic kidneys in infants and children due to early microcystic changes.

BACKGROUND: There are numerous causes of bilateral hyperechoic kidneys. Congenital disorders of glycosylation (CDGs) are a rapidly growing family of inherited disorders due to defects in the synthesis of the glycans of glycoproteins or other glycoconjugates. OBJECTIVE: To describe renal sonographic abnormalities in CDG type I in infants and children. MATERIAL AND METHODS: A retrospective study of renal US in 12 infants and children: 8 CDG-Ia (6 multivisceral forms, 2 neurological forms), 2 CDG-Ib, and 2 CDG-Ix, with detailed functional renal tests in 6. Histology of the kidneys of one 35-week fetus with CDG-Ia was available. RESULTS: Renal US was normal in the two children with the neurological form of CDG-Ia. All patients with the multivisceral form of CDG-Ia or with CDG-Ib showed increased cortical echogenicity, and/or abnormal pyramids (small +/- hyperechoic). The two patients with CDG-Ix showed predominant involvement of the medulla, with inverted corticomedullary differentiation in one. Kidney size was normal in all but two patients. The fetal kidneys exhibited diffuse microcysts arising from the distal tubules. CONCLUSIONS: Hyperechoic kidneys are common in CDG-I patients, contrasting with grossly preserved renal function. The US pattern seems to differ slightly according to the type of CDG-I, and is consistent with microcystic changes of the renal parenchyma, which occur prenatally, and may be due to ciliary dysfunction secondary to altered glycosylation of tubular glycoproteins. CDG-I, which remains largely underdiagnosed at present, should be added to the causes of hyperechoic kidneys in children, especially in cases of multivisceral involvement, after ruling out other more frequent causes.

Abdominal ultrasonography in inheredited diseases of carbohydrate metabolism.

PURPOSE: To determine the usefulness of abdominal sonography in inherited diseases of carbohydrate metabolism. MATERIALS AND METHODS: Thirty patients (age range, 4 months to 27 years) with glycogen storage diseases, galactosemia, disorders of fructose metabolism were studied with sonography. Echogenicity of the liver, sonographic dimensions of liver, kidneys and spleen were evaluated. Plasma blood parameters (ALT, AST, total cholesterol, triglycerides) were determined. RESULTS: Liver was enlarged in 21/22 patients (95.4%) with glycogen storage diseases, in both subjects with disorders of fructose metabolism, and in 2/6 patients (33.3%) with galactosemia. Hepatic echogenicity was increased in 20/22 patients (90.9%) with glycogen storage diseases, and in the subject with hereditary fructose intolerance. Patients with galactosemia did not show increased liver echogenicity. Both kidneys were enlarged in 8/17 patients (47.0%) with glycogen storage disease type I. Subjects with increased hepatic echogenicity exhibited higher plasma concentrations of any blood parameter than the others with normal echogenicity (p<0.05). CONCLUSIONS: Sonography can be useful in identification of inherited diseases of carbohydrate metabolism even if further examinations are necessary for an ultimate diagnosis.

18Fluoro-2-deoxyglucose (18FDG) PET scan of the brain in propionic acidemia: clinical and MRI correlations.

The clinical data and the imaging findings of the positron emission tomography (PET) and the magnetic resonance imaging (MRI) studies in five patients, previously diagnosed to have propionic acidemia, were retrospectively reviewed. The patients were all normal at birth. The first clinical signs, typically hypotonia and failure to thrive, appeared during the first 2 years of life. With progression of the disease, the neurological findings consisted of variable degrees of dementia and extrapyramidal symptoms, notably dystonia, choreoathetosis and rigidity of variable degrees. Initial cerebral PET and MRI studies were normal. Follow-up MRI examinations showed progressive basal ganglia degeneration, with evidence of atrophy and signal abnormalities within the caudate nuclei and the putamina. The thalamic structures were normal. The PET studies demonstrated increased uptake in the basal ganglia and thalami, followed by decreased uptake in the basal ganglia at a later stage of the disease. The structural (MRI) and the functional (PET) studies of the brain were found to be complementary in the evaluation of propionic acidemia, and were in good correlation with the clinical findings.

Cerebellar hypoplasia in children with the carbohydrate-deficient glycoprotein syndrome.

We describe seven children with the carbohydrate-deficient glycoprotein syndrome, an autosomal recessive inborn error of protein glycosylation characterised by failure to thrive, neurological dysfunction and a unique pattern of physical abnormalities. Neuro-radiological investigations revealed cerebellar hypoplasia in all seven children. Two children also developed supratentorial atrophy following episodes of neurological deterioration.

CT and MR of the brain in the diagnosis of organic acidemias. Experiences from 107 patients.

The results of CT and/or MRI of the brain in 107 patients with different types of organic acidemia are presented. The CSF spaces were wide in more than two-thirds of the patients, in 46 slightly-to-moderately and in 26 markedly-to-severely dilated. Marked widening of the operculae was found in all 5 patients with glutaric acidemia type 1, but open opercula was also found in other organic acidemias. White matter changes were found in about half the patients, in 28 mildly-to-moderately pronounced, in another 28 marked or severe. Basal ganglia or central pathway pathology was seen in a total of 34 patients, i.e. 32%. These changes in 25 patients involved the caudate and/or lentiform nuclei: in 14 cases the T2 signal was increased and volume loss was present, in 9 cases increased T2 signal with preserved volume was found (in one of these the changes were transient). In 2 patients, both with ethylmalonic aciduria (cause unknown), only small high T2 spots were seen in the caudate heads and the putamina. In 4 patients, all suffering from methylmalonic acidemia, only the globus pallidus was affected. In 3 patients, all with beta-ketothiolase deficiency, high T2 intensity changes were seen only in the postero-lateral putamina. The remaining 8 patients represent a variety of different locations of lesions. The CT or MRI findings in many patients with organic acidemias should alert the radiologist that a neurometabolic disorder may be present; in some cases the location and appearance of the lesions may even suggest the correct diagnosis.

Hypertrophic obstructive cardiomyopathy in a neonate with the carbohydrate-deficient glycoprotein syndrome.

The carbohydrate-deficient glycoprotein (CDG) syndrome in its most severe form (neonatal olivopontocerebellar atrophy) is a life-threatening multisystem disease. We report a neonate who was referred for cardiological assessment because of respiratory distress, a murmur and episodes of desaturation. After initial spontaneous improvement he presented at 9 weeks with evidence of a severe hypertrophic obstructive cardiomyopathy (HOCM). The diagnosis of CDG syndrome was suggested by the characteristic dysmorphic features, hypotonia, visual inattention and severe failure to thrive; it was confirmed by electrophoresis of serum transferrin. HOCM can be a feature of the CDG syndrome, in addition to the (previously reported) pericardial effusions.